1. Field of Invention
The field of the currently claimed embodiments of this invention relates to methods of producing curved, folded or reconfigurable structures and the curved, folded or reconfigurable structures.
2. Discussion of Related Art
Thin films with heterogeneous mechanical properties such as modulus, thickness or stress will spontaneously assemble into 3D structures (Bowden, N., Brittain, S., Evans, A. G., Hutchinson, J. W., and Whitesides, G. M. Spontaneous formation of ordered structures in thin films of metals supported on an elastomeric polymer. Nature 393, 146-149 (1998); Mahadevan, L. and Rica, S. Self-organized origami. Science 307, 1740 (2005); Jamal, M., Bassik, N., Cho, J.-H., Randall, C. L., and Gracias, D. H. Directed growth of fibroblasts into three dimensional micropatterned geometries via self-assembling scaffolds. Biomaterials 31, 1683-1690 (2010)). Several studies have sought to drive the self-assembly of polymeric thin films by inducing heterogeneities in material composition (Bates, F. S. and Fredrickson, G. H. Block copolymers-designer soft materials. Phys. Today 52, 32-38 (1999); Harris, K. D., Bastiaansen, C. W. M., and Broer, D. J. A glassy bending-mode polymeric actuator which deforms in response to solvent polarity. Macromol. Rapid Comm. 27, 1323-1329 (2006); Klein, Y., Efrati, E., and Sharon, E. Shaping of elastic sheets by prescription of non-Euclidean metrics. Science 315, 1116-1120 (2007)). Self-assembly techniques have also previously been shown to spontaneously curve and fold two-dimensional (2D) micropatterned polymeric templates into 3D structures (Guan, J., He, H., Hansford, D. J., and Lee, L. J. Self-folding of three-dimensional hydrogel microstructures. J Phys. Chem. B 109, 23134-23137 (2005); Azam, A., Laflin, K. E., Jamal, M., Fernandes, R., and Gracias, D. H. Self-folding micropatterned polymeric containers. Biomed Microdevices 13, 51-58 (2011); Jeong, K.-U., et al. Three-dimensional actuators transformed from the programmed two-dimensional structures via bending, twisting and folding mechanisms. J. Mater. Chem. 21, 6824-6830 (2011); Stoychev, G., Puretskiy, N., and Ionov, L. Self-folding all-polymer thermoresponsive microcapsules. Soft Matter 7, 3277-3279 (2011)). Yet, the self-assembly of structures with integrated microfluidic networks to enable the delivery of chemicals in curved geometries and the development of vascularized 3D systems remains a significant challenge (Borenstein, J. T., et al. Microfabrication technology for vascularized tissue engineering. Biomed. Microdevices 4, 167-175 (2002); Andersson, H. and van den Berg, A. Microfabrication and microfluidics for tissue engineering: state of the art and future opportunities. Lab Chip 4, 98-103 (2004); Kelm, J. M., et al. Design of custom-shaped vascularized tissues using microtissue spheroids as minimal building units. Tissue Eng. 12, 2151-2160 (2006); McGuigan, A. P. and Sefton, M. V. Vascularized organoid engineered by modular assembly enables blood perfusion. Proc. Natl Acad. Sci. USA 103, 11461-11466 (2006); Griffith, L. G. and Swartz, M. A. Capturing complex 3D tissue physiology in vitro. Nat. Rev. Mol. Cell Biol. 7, 211-224 (2006)). Conventional microfluidic systems are typically built using layer-by-layer lithographic patterning methods on inherently planar substrates. Hence, while engineered microfluidic systems afford the manipulation of small liquid volumes for a variety of applications (Gravesen, P., Branebjerg, J., and Jensen, O. S. Microfluidics-a review. J. Micromech. Microeng. 3, 168-182 (1993); Beebe, D. J., Mensing, G. A., and Walker, G. M. Physics and applications of microfluidics in biology. Annu. Rev. Biomed. Eng. 4, 261-286 (2002); Whitesides, G. M. The origins and the future of microfluidics. Nature 442, 368-373 (2006)), they are typically confined to block-like devices. Thus in order to self-assemble microfluidic systems into 3D geometries, there remains a need for methods to produce curved, folded and/or self-assembled structures and for the improved structures.